Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-62911Unknown / EvaluatingCritical (raw)CVSS 8.0CWE-294
Microsoft Exchange Server Elevation of Privilege Vulnerability
Published: 11 Aug 2026•Last updated: 11 Aug 2026, 12:30 PM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
8.0Critical (raw)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.7%0.007
Percentile52nd
Weakness type
CWE-294
No further CWE recorded
Remediation
Patch status unknown
KB5121576, KB5121573, KB5121574, KB5121575
Why It Matters
Analysis dossierWhy It Matters
Authentication bypass by capture-replay in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
SOC priority
High
Actively exploited
No
Publicly disclosed
Unknown
Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; No confirmed exploitation signal in current enrichment
Affected Products & Remediation
4 source-backed productsAffected products and versions (source)
- Microsoft Exchange Server 2016 Cumulative Update 23 · version range not provided by source · Microsoft MSRC · Source
- Microsoft Exchange Server Subscription Edition RTM · version range not provided by source · Microsoft MSRC · Source
- Microsoft Exchange Server 2019 Cumulative Update 15 · version range not provided by source · Microsoft MSRC · Source
- Microsoft Exchange Server 2019 Cumulative Update 14 · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBKB5121576, KB5121573, KB5121574, KB5121575
Vendor or catalog guidance (source)
- Microsoft MSRC: Install the security update KB5121576 listed by MSRC
- Microsoft MSRC: Install the security update KB5121573 listed by MSRC
- Microsoft MSRC: Install the security update KB5121574 listed by MSRC
- Microsoft MSRC: Install the security update KB5121575 listed by MSRC
Known exploitation (source facts)
Only what a source states. Unknown means no source has said either way; it is not "not exploited".
- CISA KEV
- Unknown
- Exploited (source statement)
- No
- Publicly disclosed (source)
- Unknown
Suggested hunting (rule-based inference)
SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.
Matched microsoft-enterprise (Affected product: Microsoft Exchange Server 2016 Cumulative Update 23, Vendor: Microsoft); user-interaction-client (CVSS AV:N, CVSS UI:R)
Exposure
- Identify affected Microsoft products and compare local builds with the MSRC advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · The MSRC product/build mapping establishes applicability. · Rule microsoft-enterprise
- Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client
Exploitation evidence
- Review the advisory's documented behavior on matching hosts before selecting a hunt.Telemetry: DeviceProcessEvents · Product family alone does not justify a CVE-specific detection. · Rule microsoft-enterprise
Show more (2)
Exploitation evidence
- Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client
Response
- Confirm the source-stated KB or mitigation on matching assets.Telemetry: DeviceTvmSoftwareVulnerabilities · A post-update inventory check verifies remediation. · Rule microsoft-enterprise
CISA KEV Record
CISA KEV status was not determined for this record.
Change History & Source Data
— No recorded material change
- CNA / source
- secure@microsoft.com
- Record status · verification
- UPDATED · Microsoft primary source linked
- CPE
- cpe:2.3:a:microsoft:exchange_server:2016:-:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_1:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:*
Evidence & Provenance
Linked by the query's stored exact CVE association. Review required tables and validation status before use.
Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-62911
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-62911
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-62911"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel descSchema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Correlated briefings
SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.